The Macellum Magnum or "Great Market" of Nero, constructed on the Caelian Hill in 59 AD. Shown here in remarkable detail on dupondii coins of Nero, the two-storey colonnaded market complex can be seen with its central circular tholos topped by an impressive dome. #LostRome

Though on a much grander scale, Nero's macellum seems to have followed the traditional layout of ancient urban markets, with its enclosed colonnaded square. A feature that would carry through to the medieval exchange or bourse. #LostRome

The central circular or octagonal structure is also a common feature, perhaps holding statues of the emperor or deities of trade and sanctifying the market space. The macellum at Leptis Magna for comparison. #LostRome

Amazingly, the church of Santo Stefano al Monte Celio is thought to now stand on the spot once occupied by Nero’s Macellum, its distinctive circular structure perhaps evolving from the market’s circular tholos. #LostRome

Finally, we can even say hello to a trader that worked in the Great Market. Lucius Calpurnius Daphnus was a silversmith (argentarius) at the Macellum Magnum. #LostRome